SUMMARY The effects and reliability of a simple method of contrast two-dimensional echocardiographic delineation of myocardium after intracoronary injections were evaluated in closed-chest dogs. Multiple injections of an agitated saline-Renografin (meglumine diatrizoate) mixture (3:2 ratio, 2-ml bolus) into the left main coronary artery as well as at different sites of the left anterior descending and circumflex coronary arteries were studied in several short-axis and long-axis cross sections of the left ventricle. These contrast injections opacified specific regions of left ventricular myocardium depending on the site of injection. Contrast injection into the left main coronary artery provided a clear, echo-free outline (negative contrast) of underperfused myocardium distal to the coronary occlusion. Reproducibility studies of the extent of involved zones measured in echocardiographic cross sections indicated high intra-and interobserver correlation coefficients (r = 0.97 and 0.97). The effects of the intracoronary injection of contrast material appeared minor and brief. ECG ST-T changes lasted 49.4 ± 36.7 seconds, aortic systolic pressure was reduced by 7.6 ± 4.4% for 18.9 ± 4.8 seconds, and the peak rate of left ventricular pressure rise decreased by 14.3 ± 2.6%, but returned to control levels within 19.4 ± 6.1 seconds. The zone of left ventricular asynergy after coronary occlusions was also delineated by cross-sectional echocardiography and corresponded to the contrast-outlined underperfused zone (negative contrast). This new intracoronary echocardiographic technique has only minor hemodynamic consequences and provides reliable quantitation of underperfused and dysfunctioning zones after experimental coronary occlusions. Further investigation and validation of this method may provide useful characterization of the extent and severity of myocardial ischemia and infarction.THE PRIMARY application of contrast echocardiography has been in qualitative studies of the heart and determination of intracardiac defects or shunts'6 and assessment of tricuspid regurgitation.7-"0 The concept of injecting contrast material into the cardiac chambers and analyzing contrast washout in echocardiographic images has been examined in the hope of providing a noninvasive measurement of blood flow. "I Only scant attention has been given to the potential of contrast echocardiography for study of the extent op appropriate microbubbles or fluids that can safely cross the lung and permit study of left ventricular and septal myocardium while being injected intravenously or into the right chamber."'-"'We developed a simple myocardial contrast echocardiographic method that could be readily applied in closed-chest dogs with coronary occlusions. When it appeared that intracoronary injection of an agitated mixture of saline and Renografin (meglumine diatrizoate) provided consistent myocardial opacification and satisfactory outline of acutely ischemic and dysfunctioning myocardium in two-dimensional crosssectional images, we undertook to eva...

he major complications of atrial fibrillation (AF) are hemodynamic compromise and thromboembolism; 6-24% of all ischemic strokes have been attributed to AF. 1,2 In these patients, the left atrium (LA), especially the left atrial appendage (LAA), is the presumed site of thrombus formation and a source of arterial thrombus. 3 Transesophageal echocardiography (TEE) is a potentially useful diagnostic imaging modality because it enables reliable assessment of LA thrombus and LAA flow velocity (LAAFV), 4 but the ability of LAAFV alone to predict LA and LAA thrombus in patients with AF remains controversial. [5][6][7][8] Although the risk of embolism is thought to be lower with atrial flutter (AFL), 9-11 recent TEE studies have demonstrated an unexpectedly high incidence of atrial thrombus formation. 12-15 LAA blood drainage is an important factor in the pathogenesis of local flow stasis and thrombus formation, and we hypothesized that in both AF and AFL the LAA blood drainage was reduced when the frequency of LAA movement increased. Thus, we examined whether or not LAA flow time (LAAFT), the new index of LAA movement and defined as the average duration of LAA flow with emptying and filling waves, is a useful predictor of thrombus formation.The aim of the present study was to evaluate the relationship between LAA function and the incidence of LA thrombus in patients with nonvalvular chronic AF and AFL. Methods Study PatientsFrom April 1995 to May 2000, we retrospectively reviewed patients with nonvalvular chronic AF and AFL who had undergone TEE. Patients with left ventricular (LV) systolic dysfunction (LV ejection fraction <0.5) and patients undergoing anticoagulant therapy were excluded. Nonvalvular chronic AF was defined by conventional electrocardiogram (ECG) on 2 occasions separated by at least 1 month and by the absence of rheumatic heart disease as determined by echocardiography. Lone AF was defined by excluding coronary artery disease (based on clinical or laboratory criteria), hyperthyroidism, valvular heart diseases, congestive heart failure, cardiomyopathy, chronic obstructive pulmonary disease, cardiomegaly on chest X-ray, history of hypertension, age over 60 years, insulin-dependent diabetes, AF only during trauma or surgery, and acute medical illness. 16 Sixty-two patients (53 male, 9 female; mean age, 60.0± 9.7 years) entered the study: 50 had chronic AF and 12 had AFL. The patients with AF were divided into 2 groups: lone AF (n=14) and non-lone AF (n=36). The relationship between the left atrial appendage (LAA) function, as assessed by transesophageal echocardiography, and the incidence of left atrial thrombus was evaluated in 62 patients with nonvalvular chronic atrial fibrillation (AF; n=50) and atrial flutter (AFL; n=12). It was hypothesized that in both AF and AFL not only the LAA flow velocity (LAAFV), but also the frequency of the LAA movement (the LAA flow time, LAAFT) is a major contributing factor to thrombus formation. LAAFT was defined as the average duration of LAA flow with emptying and fil...

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Myocardial contrast two-dimensional echocardiography was used in 21 closed chest dogs to assess its ability to delineate the extent of underperfused acutely ischemic myocardium. An agitated saline-Renografin echocardiographic contrast agent was injected into the left main coronary artery after left anterior descending coronary artery occlusion, and the size of the contrast echo-free area characterizing the perfusion defect was outlined in short-axis cross sections of the left ventricle. In 13 dogs, monastral blue dye was injected after 45 minutes of coronary artery occlusion and before sacrifice to provide anatomic delineation of underperfused zones in equivalent sections. Perfusion defects assessed by contrast two-dimensional echocardiography correlated well with those delineated by monastral blue dye (r = 0.91). Contrast echocardiographic study was also performed in eight other dogs at 5 hours of occlusion, after which infarct size was measured with triphenyl-tetrazolium-chloride. Contrast echocardiographic outline of the perfusion deficiency correlated but slightly overestimated the extent of necrosis (r = 0.88). It is concluded that contrast two-dimensional echocardiography can detect and outline the underperfused "risk area" during acute coronary artery occlusion, and may also permit assessment of the extent of myocardial infarction.

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